An NBN Co's Road Muster truck has arrived in Tumut this morning to provide temporary broadband connectivity and internet access to residents, following fire damage to the local infrastructure exchange.

About 3pm on Friday a fire broke out in the exchange in Tumut that caused "significant damage to communications infrastructure", a NSW Police statement said.

Police have arrested a man in Tumut.

It is expected to take a "number of days" to restore the affected Telstra service due to the severity of the damage.

"The Road Muster truck ... will be roaming throughout the day," said, head of NBN local for NSW and Queensland, Ryan Williams.

"The vehicle is equipped with a Sky Muster™ satellite dish that can provide a valuable WiFi connection for community members and emergency workers.

" .. [It] is part of NBN Co's suite of temporary network equipment that can be deployed to support communities in emergency events, particularly when telecommunications are affected."

NBN is working closely with Telstra to restore affected services.

A NSW Police statement said police were called and an investigation was commenced by officers from the Riverina Police District.

"Meanwhile, later in the day three vehicles were damaged by fire on Lambie Street, Tumut," the statement said.

"Police were called, and a description was given of a man who was later arrested by officers on Adelong Street."

The man was taken to Wagga Police Station before being taken to Wagga Base Hospital for treatment to an existing health condition.